Such a spraying device is used for example for the manual painting of any article. It may for example be an electrostatic powder-coating device. Such a spraying device generally comprises a spray gun through which the coating product is propelled, a control module allowing the monitoring and adjustments necessary for propelling this coating product and an assembly of pipes and cables connecting the spray gun to the module. For its part, the spray gun comprises a spray nozzle, a voltage multiplier device making it possible to generate a high voltage and possibly a button for adjusting the flow rate of the propelled product and the shape of the spray cloud. Such a spraying device is revealed for example by U.S. Pat. No. 5,351,903.
Generally, the application spray gun is held by an operator and both are located in a booth through which the articles to be painted file along. The control module is, however, located outside the booth for reasons of standards and soiling.
To paint an article properly, it is necessary for a certain number of parameter, for example the flow rate of paint, the high-voltage or current level, the shaping air streams, etc, to be complied with. Adjustments are envisaged for adapting these parameters to the article and to the paint used.
In the case of hand-held spray guns, the operator has two means of adjusting these parameters. In case, he adjusts the flow rate of paint and the shaping airstreams on an adjustment button on the spray gun. In the document U.S. Pat. No. 5,351,903, this adjustment button takes the form of a trigger associated with a potentiometer. In the second case, he must go outside the booth to perform the required adjustments.
To paint articles, an operator has to wear overalls, a hood, gloves, protective goggles and a mask. This considerably impedes his movements. Moreover, these protective items are more or less covered with paint and on leaving the booth, there is a high risk of soiling.
When the adjustments are made on the button of the spray gun, the operator alters his paint jet visually and it is difficult to reproduce the same parameters for two successive identical articles.
Furthermore, for reasons of handleability of the spray gun and for reasons of reliability thereof, the number of wires of the cable connecting the control module to the spray gun is deliberately limited. Specifically, the larger the cross section of this cable, the stiffer it is and the more it will impede the operator. Moreover, the cables make the spray gun heavier.
The present invention also relates to sprayers which are generally found mounted on the end of an arm of a multi-axis machine. These sprayers comprise among other things a turbine rotating at high speed or a flow meter and a paint flow rate regulator. The document FR-2 762 237 describes such a sprayer.
The speed of rotation of the turbine of the sprayer must be accurately controlled. To do this, this speed is firstly measured and then transferred via a cable to a regulating card which compares it with a preset speed, calculates the discrepancy between the preset and the measurement and deduces therefrom a command to be sent to an actuator acting on the speed of the turbine. This actuator is generally a proportional valve located in the rack of the multi-axis machine.
Likewise, the flow rate must be controlled accurately. For this purpose, a flow meter measures the instantaneous value of the flow rate, this value being transferred via a cable to a regulating card. This value is compared with the flow rate preset. The discrepancy between these two values is used to deduce a correction command which must be sent to the actuator in this instance a proportional valve whose pressure outlet acts on a flow rate regulator.